vectorAdd.cpp

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/**
 * Vector addition: C = A + B.
 *
 * This sample is a very basic sample that implements element by element
 * vector addition. It is the same as the sample illustrating Chapter 2
 * of the programming guide with some additions like error checking.
 */

#include <stdio.h>
#include <cmath>

// For the CUDA runtime routines (prefixed with "cuda_")
#include <cuda.h>
#include <cuda_runtime.h>

// helper functions and utilities to work with CUDA
#include <helper_functions.h>

#include <nvrtc_helper.h>

/**
 * Host main routine
 */
int main(int argc, char **argv) {
  char *cubin, *kernel_file;
  size_t cubinSize;
  kernel_file = sdkFindFilePath("vectorAdd_kernel.cu", argv[0]);
  compileFileToCUBIN(kernel_file, argc, argv, &cubin, &cubinSize, 0);
  CUmodule module = loadCUBIN(cubin, argc, argv);

  CUfunction kernel_addr;
  checkCudaErrors(cuModuleGetFunction(&kernel_addr, module, "vectorAdd"));

  // Print the vector length to be used, and compute its size
  int numElements = 50000;
  size_t size = numElements * sizeof(float);
  printf("[Vector addition of %d elements]\n", numElements);

  // Allocate the host input vector A
  float *h_A = reinterpret_cast<float *>(malloc(size));

  // Allocate the host input vector B
  float *h_B = reinterpret_cast<float *>(malloc(size));

  // Allocate the host output vector C
  float *h_C = reinterpret_cast<float *>(malloc(size));

  // Verify that allocations succeeded
  if (h_A == NULL || h_B == NULL || h_C == NULL) {
    fprintf(stderr, "Failed to allocate host vectors!\n");
    exit(EXIT_FAILURE);
  }

  // Initialize the host input vectors
  for (int i = 0; i < numElements; ++i) {
    h_A[i] = rand() / static_cast<float>(RAND_MAX);
    h_B[i] = rand() / static_cast<float>(RAND_MAX);
  }

  // Allocate the device input vector A
  CUdeviceptr d_A;
  checkCudaErrors(cuMemAlloc(&d_A, size));

  // Allocate the device input vector B
  CUdeviceptr d_B;
  checkCudaErrors(cuMemAlloc(&d_B, size));

  // Allocate the device output vector C
  CUdeviceptr d_C;
  checkCudaErrors(cuMemAlloc(&d_C, size));

  // Copy the host input vectors A and B in host memory to the device input
  // vectors in device memory
  printf("Copy input data from the host memory to the CUDA device\n");
  checkCudaErrors(cuMemcpyHtoD(d_A, h_A, size));
  checkCudaErrors(cuMemcpyHtoD(d_B, h_B, size));

  // Launch the Vector Add CUDA Kernel
  int threadsPerBlock = 256;
  int blocksPerGrid = (numElements + threadsPerBlock - 1) / threadsPerBlock;
  printf("CUDA kernel launch with %d blocks of %d threads\n", blocksPerGrid,
         threadsPerBlock);
  dim3 cudaBlockSize(threadsPerBlock, 1, 1);
  dim3 cudaGridSize(blocksPerGrid, 1, 1);

  void *arr[] = {reinterpret_cast<void *>(&d_A), reinterpret_cast<void *>(&d_B),
                 reinterpret_cast<void *>(&d_C),
                 reinterpret_cast<void *>(&numElements)};
  checkCudaErrors(cuLaunchKernel(kernel_addr, cudaGridSize.x, cudaGridSize.y,
                                 cudaGridSize.z, /* grid dim */
                                 cudaBlockSize.x, cudaBlockSize.y,
                                 cudaBlockSize.z, /* block dim */
                                 0, 0,            /* shared mem, stream */
                                 &arr[0],         /* arguments */
                                 0));
  checkCudaErrors(cuCtxSynchronize());

  // Copy the device result vector in device memory to the host result vector
  // in host memory.
  printf("Copy output data from the CUDA device to the host memory\n");
  checkCudaErrors(cuMemcpyDtoH(h_C, d_C, size));

  // Verify that the result vector is correct
  for (int i = 0; i < numElements; ++i) {
    if (fabs(h_A[i] + h_B[i] - h_C[i]) > 1e-5) {
      fprintf(stderr, "Result verification failed at element %d!\n", i);
      exit(EXIT_FAILURE);
    }
  }

  printf("Test PASSED\n");

  // Free device global memory
  checkCudaErrors(cuMemFree(d_A));
  checkCudaErrors(cuMemFree(d_B));
  checkCudaErrors(cuMemFree(d_C));

  // Free host memory
  free(h_A);
  free(h_B);
  free(h_C);

  printf("Done\n");

  return 0;
}